The West Nile fever virus (WNV) was first identified in man in 1937 in Uganda in the West Nile Province (Zeller H. G., Med. Trop., 1999, 59, 490-494).
Widespread in Africa, it is also found in India, Pakistan and the Mediterranean basin and was identified for the first time in the USA in 1999 in New York City (Anderson J. F. et al., Science, 1999, 286, 2331-2333).
The West Nile fever virus affects birds as well as reptiles, mammals, together with man.
The disease is characterized in birds by an attack of the central nervous system and death. The lesions include encephalitis, hemorrhages in the myocardium and hemorrhages and necroses in the intestinal tract.
In chickens, experimental infections by subcutaneous inoculations of the West Nile fever virus isolated on crows led to necrosis of the myocardium, nephritis and pneumonia 5 to 10 days after inoculation and moderate to severe encephalitis 21 days after inoculation (Senne D. A. et al., Avian Disease, 2000, 44, 642-649).
The West Nile fever virus also affects horses, especially in North Africa and Europe (Cantile C. et al., Equine Vet. J., 2000, 32 (1), 31-35). These horses reveal signs of ataxia, weakness of the rear limbs, paresis evolving towards tetraplegia and death. Horses and camels are the main animals manifesting clinical signs in the form of encephalitis.
Anti-WNV antibodies were detected in certain rodents, in livestock, especially bovines and ovines, as well as in domestic animals, especially in the dog (Zeller H. G., Med. Trop., 1999, 59, 490-494; Lundstrom J. O., Journal of Vector Ecology, 1999, 24 (1), 1-39).
The West Nile fever virus also affects with a number of symptoms the human species (Sampson B. A., Human Pathology, 2000, 31 (5), 527-531; Marra C. M., Seminars in Neurology, 2000, 20 (3), 323-327).
The West Nile fever virus is transmitted to birds and mammals by the bites of certain mosquitoes (e.g. Culex, Aedes, Anopheles). Direct transmission may happen from WNV infected subject to healthy subject by oral transmission (prey and transmission through colostrum) and blood/organ vectored transmission.
Wild and domestic birds are a reservoir for the West Nile virus and a propagation vector as a result of their migrations.
The virions of the West Nile fever virus are spherical particles with a diameter of 50 nm constituted by a lipoproteic envelope surrounding an icosahedric nucleocapsid containing a positive polarity, single-strand RNA.
A single open reading frame (ORF) encodes all the viral proteins in the form of a polyprotein. The cleaving and maturation of this polyprotein leads to the production of about ten different viral proteins. The structural proteins are encoded by the 5′ part of the genome and correspond to the nucleocapsid designated C (14 kDa), the envelope glycoprotein designated E (50 kDa), the pre-membrane protein designated prM (23 kDa), the membrane protein designated M (7 kDa). The non-structural proteins are encoded by the 3′ part of the genome and correspond to the proteins NS1 (40 kDa), NS2A (19 kDa), NS2B (14 kDa), NS3 (74 kDa), NS4A (15 kDa), NS4B (29 kDa), NS5 (97 kDa).
Parrish C. R. et al. (J. Gen. Virol., 1991, 72, 1645-1653), Kulkarni A. B. et al. (J. Virol., 1992, 66 (6), 3583-3592) and Hill A. B. et al. (J. Gen. Virol., 1992, 73, 1115-1123), on the basis of the vaccinia virus, constructed in vivo expression vectors containing various inserts corresponding to nucleotide sequences coding for non-structural proteins of the Kunjin virus, optionally associated with structural proteins. These vectors were administered to mice to evaluate the immune cell response. The authors stress the importance of the cell response, which is essentially stimulated by non-structural proteins and especially NS3, NS4A and NS4B. These articles reveal the difficulty in providing a good vaccination strategy against West Nile fever.
Reference is also made to WO 02/081754 published Oct. 17, 2002, from PCT/US02/10764, filed Apr. 4, 2002, with a claim of priority from U.S. application Ser. No. 09/826,115, filed Apr. 4, 2001. The PCT claims a status of continuation-in-part from U.S. application Ser. No. 09/826,115. It further states that U.S. application Ser. No. 09/826,115 is a continuation-in-part of U.S. application Ser. No. 09/701,536, filed Nov. 29, 2000. It even further states that U.S. application Ser. No. 09/701,536 is the National Stage of PCT/US99/12298, filed Jun. 3, 1999, with a claim of priority to U.S. provisional application Ser. No. 60/087,908.
It would be advantageous to provide improved immunogenic and vaccine compositions against WNV, and methods for making and using such compositions, including such compositions that provide for differential diagnostic methods, assays and kits, and thus, differential diagnostic methods, assays and kits.